Soot disposal process and apparatus



Oct. 20, 1931. w. R. WHITNEY 1,828,631

500T DISPOSAL PROCESS AND APPARATUS Filed March 13, 1928 inQerTtof: I I 7 Will IS R. Whitneg, WW

b9 as Attorneg n a Oct. 20, 1931' p UNITED STATES PATENT OFFICE WILLI IS R. WHITNEY, OF SCHEN'ECTADY, NEW YORK, ASSTGN OR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK I SOO'I. DISPOSAL PROCESS AND APPARATUS Application fi led March 13, 1928. Serial No. 261,357.

The present invention relates to smoke precipitation and in particular to the removal of precipitated matter, which for convenience will be referred to-herein as soot regardless of whether or not such matter originates from combustion. My invention, however, is particularly applicable to the precipitation of smoke from the combustion of soft coal.

Soot has been successfully precipitated from smoke in industrial plants of various kinds by passing the smoke between electrodes charged to high potentials, thereby causing the suspended particles to be drawn to one of the electrodes from which they were removed mechanically from time to time. Such. apparatus heretofore has required special attendance by an operator and for that reason has not been well suited for use with small installations.

An object of my invention is to provide an improved apparatus and method of operation for utilizing a suitable liquid for carrying away the soot, and for finally removing said set forth with greater particularity by the ap- I tention.

soot in a manner requiring a minimum of at- Soot ordinaril does not mix well with water which is t e most-conveniently available liquid for its removal and for this reason the removal of the soot with water entails difficulties.

a solvent for the oily or tarry matter which is apt to be associated with the soot and apparently by its presence prevents water from wetting the soot particles. I have discovered that by the addition to water of such solvent when soluble in the water, soot particles may be caused to be wetted by and suspended in water. I I

The novel features of my invention will be pended claims; for a better understanding of myinvention reference should be had to the following specification and the accompanying drawing which shows somewhat diagrammatically and (partly in vertical section an apparatus embo ying my invention. 4

In the device shown in the drawing, th smoke or other gas from which soot is to be precipitated, is withdrawn from a flue or These are overcome in accordancewith my invention by providing in the water other source (not shown) by aconduit 1 and thereby is conveyed to a precipitator comprising one or more stacks. Only a singlestack 2 is shown in the drawing. The stack in the arrangement illustrated constitutes a collecting electrode, the cooperating electrode I collecting electrode 2. Heating current for v the cathode filament circuit of the rectifier is furnished by a separate insulated trans former 10. A pulsating direct current is furnished by the particular form of current source here illustrated. 7

When high potential direct current is applied to the electrodes 2, 3, the electrode 3 being, preferably but not necessarily, made the positive electrode, then the soot particles coming from the "furnace or other source are caused to be deposited on the collector electrode 2. Instead of being deposited directly on the surface of the collector electrode, the soot may be "caused to be deposited upon a film of water which is directed over the interior of the stack by means illustrated as comprising nozzles 11 which are suppliedby a conduit 12. and being arranged to deliver a liquid at the upper part of the stack. Soot, however, may deposit directly on the electrode 2 and subsequently may be flushed off with a suitable liquid, such as water. The nozzles preferably are placed to direct the water'- tangentially, so as to cause a swirling and spreading ofthe water over the inside surface of the stack. 1

The current of liquid (which may be assumed ordinarily to be water) carrying with it the deposited soot is collected at the bottom end of the stack within a tank13. A solvent,

' such as acetone, alcohol or ether, for example,

which is readily miscible or soluble in water I v is introduced as may be necessary into the water in the apparatus from a container 14 through a tube 15, its flow being controlled 5 by a valve 16. The solvent need be-added only in very small proportions, depending on conditions-say, a'few tenths of one 'per cent.

The tank 13 should be chosen to be of sulficient depth to permit a substantial amount of the soot to settle and collect at the bot-tom part of the tank as indicated at 17. The solution, still carrying in suspension soot particles, is withdrawn by a pump 18 through a conduit 19 and is caused to recirculate through the conduits 20 and 21 to the precipitating stack. Some suitable means, such as a filter 22 may be provided to remove the greater part of the suspended matter before the solution is 'again supplied to the stack.

20 As the combustion of soft coal also produces various soluble gases and soluble mineral matters together with carbonaceous matter, the body of water if cyclically circulated for a considerable length of time would be- 25 come so charged with soluble products as to finally interfere with the operation ofthe process. I prefer, therefore, to continuously remove a small fraction, say about one percent, of the circulating liquid by a bleeder pipe 23, the amount of wastage being controlled by a valve 24. The liquid thus withdrawn. and other losses, are replaced by a pipe 25. which may be provided with a floatvalve 26 to automatically control the replace- 35, ment of the water. From time to time accumulations of soot deposited at the bottom of the tank 13 are removed through an outlet 27. The solvent from the container 14 need not be supplied continuously in all cases but 40 may be supplied from time to time when its content in the water isno longer suflicient to cause the soot to sink in the water.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The process of removingsoot particles from suspension in a gas which comprises carrying away said particles with water con-. taining a solvent for oily matter which is associated with said particles, thereby causing said particles to be wetted by and to mingle with the water.

2. The process of removing soot particles from suspension in a gas which comprises causing said soot articles to be carried away with a current 0 water containing a material whereby soot particles are rendered miscible with water, and separating said soot particles from the water.

3., The process of removing soot particles which comprises carrying away said particles with an aqueous solution ofacetone and causing said particles to separate from said solution. 1 V

4. The process of removing soot particles 5 from smoke which comprises precipitating said particles, carrying the particles away with water containing a fractional per cent of acetone, separating the bulk of said particles from the water and carrying away an additional amount of soot by the water re- 70 maining after said separation.

5. A smoke abatement device comprising in combination means for precipitating soot particles from a gas, means for causing said soot particles to be carried away by a liquid, 7 means for supplying to said liquid an agent for causing miscibility of said particles with said liquid and means for separating said particles from said liquid.

6. In combination, a smoke precipitation 8 apparatus, liquid means for carrying away soot particles derived from the smoke, a settling tank for receiving said liquid, means for removing from said particles matter tending to render said particlesimmiscible with said liquid, means for removing sus-- pended soot from said liquid, and means for recirculating said liquid.

7. A precipitation apparatus of the class described, including means for precipitating finely divided solid particles suspended in a gas, means comprising a liquid to carry away said precipitated particles, a tank for collecting said liquid and precipitated particles, means for dissolving from said particles matter rendering said particles immiscible with said liquid, filtration means for removing the particles from said liquid, and means for restoring said liquid, when substantially freed from said finely divided particles, to the precipitating means.

8. The process of removing soot particles from suspension in a gas which comprises carrying away said-particles with water containing a fraction of a percent of a solvent for oily matter which is associated with said particles, thereby causing said particles to be wetted by and to mingle with the Water.

In witness whereof I have hereunto set my hand this 12th day of March, 1928.

' WILLIS R. WHITNEY.

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